Vacuum cooling apparatus



J1me 195$ LE ROY A. DRoEscHER 2,

VACUUM COOLING APPARATUS Filed June '7, 1946 mmvrm L5 Pay A. DROEJCHER film ATTOFPNE Y5 Patented June 20, 1950 UNITED. STATES PATENT; oluuacs 2,512,056 i f VACUUM COOLING APPARATUS Le Roy A. Droescher,Bala -Cynwyd,IPa., assignor to C. H. Wheeler Manufacturing 00., Philadelphia, Pa., a corporation -of Pennsylvania Application June 7, 1946, -Serial him-67 5;259-

6 Claims.

- 'This invention relates to vacuum cooling apparatus and has particular reference to such apparatus in which evacuation is effected through the use of steam jet ejectors.

Steam jet refrigerating apparatus is particularly useful and economical where large quantities 'of evaporable liquids are to be used for cooling purposes as, for example, in air conditioning. However, certain characteristics of this type of apparatus make it .difiicult to secure control of temperature within narrow limits.

Theeapacity of a steam'ejector is fixed by the initial design characteristics and its capacity cannot be properly regulated by throttling the steam flow. Accordingly, there is substantially no flex-- ibility in handling different refrigeration loads for any given chilled liquid temperature. For

example, when a steam ejector is associated with a flash evaporator there exists a characteristic of operation which involves a substantially linear relationship between the quantity of cooled liquid which is delivered and the temperature thereof For example, if at rated flow of cooled flow may giverise to a temperature of 45 IF. whereas 115% of rated flow may involve a temperature of 55 F., the indicated linear relation-.

ship existing both within and Without these limits. Similarly for a fixed flow, the temperature of the cooled liquid will bear a definite relationship to the temperature of the liquid entering the evaporator. As a consequence, therefore, the

temperature of the delivered liquid is obviously critically dependent upon the refrigeration load. It sometimes happens that the requirements are such as to demand a substantially constant -temperature with varying refrigeration loads. It .is the broad object of the present invention to provide a simple system whereby very close temperature control may be secured in a system-of the type indicated while permitting substantial latitude in the quantity or initial temperature of a the liquid which is being chilled. I

This and other objects particularly relating-to details of construction and operation will become apparent from the following description read in conjunction with the accompanying drawing in which the figure represents diagrammatically-a vacuum cooling system embodying the principles of the invention.

There is indicated at '2 a hash evaporator of conventional type consisting of an ---e nclosure,-

substantially conventional.

intermediate the evaporator and the within which an .evaporable .liquidsuch-"as water is evaporated -under vacuum with attendant cooling. This-evaporator fed @with liquid from a r line "-4 which :may be either a make-up ;-line or more usually a return line for the liquid from the point of-rheat transfer thereto, suitable makeup to take careefevaporation being provided .in conventional fashion, -or ,-'if dehumidification is involved, there being proper provision :for elimination of excess liquid. The liquid from the line 4 which is to pass to the evaporator is controlled in the usual fashion by avalve 6 under thecontrol of a float 8 which maintains substantially constant the liquid level in the evaporator. The incomingliquid issprayed into the evaporator through the usual nozzles l0. Froma lowpoint in the evaporator the chilled liquid is withdrawn through a line 12 by a pump sindicated 'at l4 and is delivered thereby through the discharge line 1-5 to the point of use.

The evaporator illustrated in the figure has as- .sociated with it'a plurality ofsteam -jetejectors individually connected to theevaporator through selectively-operable valves 18, these ejectors being fed with steam in the usual fashion to produce a vacuum,for example, of the order 29.7 inches in the case of a 30 inch barometer.

To the extent so far described the system is Various combinations of ejectors, which may have-suitable'different capacities, may be used to maintain the proper outflow temperature of the liquidfrom the evaporator. Under ordinary conditions-of operation there would then exist thecharacteristics described above, i. e., the temperature of the delivered liquid would depend upon the quantity delivered in such fashion that constant temtherein so that the static head prevents flash evaporation of the warm water which .flows throughthe bypass. As will be evident, instead of permitting this warm water to mingle with the chilled waterin the evaporator the bypass may run directlyto the pump intake or to any point pump intake.

quired, i. e., a temperature less than that for which the thermostat is set. Under such conditions the thermostat, which is desirably of a sensitive type, will open the bypass valve 24 to such extent as to provide a proportion of flow.

through the bypass related to that entering the evaporator as to maintain at the output of the pump the desired temperature, 1. e., only a certain proportion of the delivered liquid passes through the evaporator nozzles to be chilled thereby to a temperature below that required,'

while the remaining liquid bypasses the evaporator to the pump intake, being mixed in the pump with the chilled liquid. If now the flow demand is reduced an automatic readjustment takes lplafce, the proportion of the bypassed liquid increasing by further opening of the valve 24 with attendant decrease of flow through the valve 6 "so that the temperature is maintained; With increase of flow the opposite action occurs, the proportion of liquid flowing through the bypass being reduced so that nevertheless'the temperatureof the liquid delivered by thep'ump remains substantially constant. I

" The foregoing operation may theoretically an 7 tinue until the'quantity demand is such that the -j'etjejec'torsin operation will he no longer able to maintain the desired chilled condition of the liquid even with the bypass 'completely' olosed.

Before this condition'is reached, therefore, an other ejector mustbe cut into the system. While :the introduction or removalof the various eject- "ors maybe effected automatically, by tie up with the condition of substantial closing or mn'opening of the bypass valve 24, this is not generally "required since an attendant"may cutthe'ejectors "i'n-orout as indicated by a siutable signal controll'ed in conjunction'with the bypassvalve, the "flow through which may be'jobserved either from 'the valveposition or by the incorporation of a suitable flowmeter. 'In'any eventjwhile throug a full range of operation different numbers of ejectors may be required, nevertheless i'n the individual ranges of operation corresponding to "particular numbers of ejectors a smooth and accurate control of the temperature is provided jirre'spective of variations in the quantity delivered by the pump l4. Thus refrigeration capaclitylrequirements intermediate between individual ejectors or plural combinations thereof may -i be obtained in accordance with theinvention. .It will be evident that the range of variation of temperature will depend solely upon the sensitivity of the thermostat control, control being easily possible to a fraction of a degree.

It will, of course, be understood that the electors or boosters may be arranged and operated in conventional fashion in conjunction with con- .ventional condensing equipment and other devices of usual type. l

r What I claim and desire to protect by Letters Patent is: I f 1. In combination, an evaporator, means for evacuating said evaporator, a supply line to said evaporator, a delivery line from saidevaporator, a bypass connecting said supply line to said delivery line, flow control means mounted in said supply linebetween said evaporator and the point 'of connection of said bypass with said'supply line, flow control means mounted in said bypass line, and means controlling said second mentioned flow control means regulating the flow of liquid through the bypass to maintain the temperature of the delivered liquid substantially constant.

2. In combination, an evaporator, means for evacuating said evaporator, a supply line to said evaporator, a. delivery line from said evaporator, a bypass connecting said supply line to said delivery line, flow control means mounted in said supply line between said evaporator and the point of connection of said bypass with said supply line, flow control means mounted in said bypass line, and means controlling said second mentioned flow control means regulating the flow of liquid through the bypass to maintain the temperature of the delivered liquid substantially constant, the exit from said (bypass being at a location under sufiicient static head to prevent flashing.

'3. In combination, an evaporator, meansfor evacuating said evaporator, a supply line to said evaporator, a delivery line from said evaporator, a bypass connecting said supply line to said'delivery line, flow control means mounted in said supply line between said evaporator and the point of connection'of said bypass with said supply line, means responsive to the liquid level in the evaporator controlling said flow control means, flow control means mounted in said bypass line, and means responsive to the temperature of the liquid in said delivery line beyond the point of its connection with said'bypass contr'ollings'aid second mentioned flow control means regulating the flow of liquid through the bypass to maintain the temperature of the delivered liquid substantially constant. 4. In combination, an evaporator, a pluralit of individually controllable means for evacuat ing said evaporator, a supply line to said evaporatoi, a delivery line from said evaporator, a by pass connecting'said supply line to said deliveryline, flow control means mounted in said supply 'flow control means mountedin said bypass line,

and means controlling said second 'mentioned flow control means regulating the flow of liquid through the bypass to maintain the temperature oi the delivered liquid substantially constant.

5. In combination, an evaporator, a plurality of individually controllable steam ejector means for evacuating said evaporator, a supply line to said evaporator, a delivery line :from said evaporator, a bypass connecting said supply line to said delivery line, flow control means mounted in said supply line between said evaporator and the point of connection of said bypass with said supply line, flow control means mounted in said bypass line, and means controlling said second mentioned flow control means regulating the flow of liquid through the bypass to maintain the temperature of the delivered liquid substantially constant.

6. In combination, an evaporator, a plurality of individually controllable means for evacuating said evaporator, a supply line to said evaporator, a delivery line from said evaporator, -a bypass connecting said supply line to said delivery line, flow control means mounted in said supply line between said evaporator and the point of connection of said bypass with said supply line, means responsive to the liquid level in the evaporator controlling said flow control means, flow control means mounted in said bypass line, and means responsive to the temperature of the liquid in said delivery line beyond the point of its connection with said bypass controlling said second mentioned flow control means regulating the flow of liquid through the bypass to maintain the temperature of the delivered liquid substantially constant.

LE ROY A. DROESCHER.

6 REFERENCES CITED The following references are of record in the file of this patent: 

